Magnetic recording of video signals is usually carried out by recording the signals in parallel tracks extending at an inclination with respect to the longitudinal edge of the tape. This is done by wrapping the tape about a recording drum or cylinder within which a head wheel, carrying transducer heads, which rotate. The particular type of recording system determines the angle of the tracks with respect to the longitudinal direction of the magnetic tape. At times it is desirable to reproduce tape which has been recorded at a given recording speed by playing back the tape at a different speed, while retaining the standard according to which the signals have been recorded. Due to the changed transport speed of the tape upon reproduction, the tracks scanned by the magnetic heads no longer will overlap the tracks as they were recorded.
Some recording systems record such that the signal data corresponding to one video field or frame are distributed over several tracks. If such a tape is then reproduced at a speed differing from the recording speed, the respective signal portions may be reproduced in a wrong sequence.
It has been proposed to read-out signals at a speed differing from recording speed by providing a memory in which signals derived from the magnetic tape, which conform to predetermined requirements, are recorded, and then read-out in accordance with the respective television standard (see U.S. Pat. Nos. 4,139,867; 4,210,938; 4,293,879). A portion of the signals recorded cannot be utilized, however, in the known method due to the transition of the magnetic head from one track to the next. The magnitude of this portion which is not read-out depends on various parameters, such as track width, gap width, and track angle, that is, the angle of inclination of the tracks with respect to the longitudinal edge of the tape. At some predetermined relationship between recording tape speed and reproduction tape speed, the system causes difficulties which are particularly severe; for example, if the tape reproduction speed is twice as high as the recording speed, then those signals which occur in the first field cannot be reproduced at all, since they are not scanned in the second field and in the subsequent field. Specific speed relationships thus should be avoided; others are preferred. In the known systems, therefore, signals must be collected from a plurality of recorded fractions of the fields so that, upon reproduction of subject matter which includes fast-moving sequences, errors and misinformation result.